Atherosclerosis is a degenerative vascular disease characterized by: 1) intimal cell proliferation, 2) margination of monocytes and their migration into the intima, 3) lipid accumulation, and 4) increased matrix deposition. Utilizing several in vivo models, we have demonstrated that both denuding arterial injury and its sequelae as well as herpesviral infection will lead to alterations in phenotypic expression of neointimal SMC when assessed by several metabolic parameters. Additionally, in the former model, we have demonstrated that regenerated endothelium can modulate the metabolism of the underlying neointima. The purpose of this research project is to investigate these processes at the cellular level. We wish to study the interactions between arterial smooth muscle cells (SMC), arterial endothelial cells (EC) and macrophage-derived foam cells in an attempt to define those factors involved in the observed modulation of arterial cells which predispose to atherosclerotic lesion development. The following hypotheses will be tested: 1) Arterial EC modify the growth and cell cycle kinetics of co-cultured arterial SMC grown in a quiescent and non-quiescent (i.e. non-modulated vs modulated) state. The presence of extracellular matrix proteins such as heparan sulfate-rich proteoglycans will modulate this effect; 2) Arterial EC modulate cholesterol and proteoglycan metabolism in co-cultured arterial SMC. Eicosanoids from stimulated arterial EC such as PGI2 or PGE2 may alter cholesteryl ester (CE) hydrolysis and synthesis in co-cultured arterial SMC; 3) Macrophage-derived foam cell products directly activate or induce the release of proteases in the subendothelial space, thus affecting endothelial integrity, thrombosis and tissue remodeling; and 4) Infection of human arterial SMC with human herpesviruses (HSV-1 and/or cytomegalovirus) will lead to altered cholesterol CE metabolism and accumulation, similar to the effects observed with Marek's disease herpesvirus on chicken arterial SMC and arteries. Our long term goals are to provide evidence that cells of the atherosclerotic lesion interact in such a way as to promote cell proliferation, matrix protein deposition, and lipid accretion. Furthermore, the presence of human herpesviruses in SMC may "transform" these cells such that they no longer can effectively metabolize CE or control their growth rate. It is anticipated that the identification of those mechanism(s) which regulate the interaction of vascular cells in vitro will undoubtedly provide valuable information and extend our present knowledge of those processes involved in atherogenesis.